Process for coloring polypropylene



and polyazo dyes.

' according to the present invention and listed in the Color United States Patent 3,097,044 PROCESS FOR COLORING POLYPROPYLENE Thomas Skeuse, Purdys, N.Y., assignor to Geigy Chemical Corporation, Greenburgh, N.Y., a corporation of Delaware No Drawing. Filed Apr. 4, 1960, Ser. No. 19,471 9 Claims. (Cl. 8-55) This invention relates to a method of coloring polypropylene, especially fibers of polypropylene. Heretofore, such fibers of polypropylene could not be colored commercially, since attempted dyeings and paddings were obtained with poor color value and/ or poor light tastness properties. Surprisingly, it has now been found that polypropylene can be dyed and padded successfully using mordant dyes by the method of the present invention.

It is an object of the invention to provide a method of dyeing polypropylene and in particular, polypropylene fibers, so that the dyed material exhibits high color value and/or good light fastness. It is a further object of the invention to provide dyed polypropylene and in particular, dyed polypropylene fiber whose color value is of good quality and whose light fastness properties are commercially acceptable.

The method of the invention involves the process, which requires the simultaneous interaction of dye, metal salt, acid and fiber in the dye bath. Any mordant dye which is amenable to the process is within the scope of the present invention. Other metal salts besides chrome salts may be used, e.g. cobalt, nickel, etc. salts are useful. Thus, the dyes usable according to the present invention are the known dyes which are capable of combining with various metals preferably with chromium, to form metal complexes. Such dyes are known in the art as mordant dyes. A great variety of chemical types fall within the class of mordant dyes; they are all characterized by a salt-forming group and a group capable of forming a coordinated compound with a metallic atom in such relative position that an internal complex salt can be produced. Conditions for the formation of heterocyclic 5- or 6-membered rings favor the production of such complexes. Mordant dyes are represented in almost all dye classes such as nitnoso dyes, mono-azo dyes, disazo dyes Examples of specific dyestufis usable Index of the American Association of Textile Chemists and Colorists, 2nd edition, vol. 1, pp. 1405, ft. (1956), are: Acid Red 12 (mordant dye: chrome in dye bath); Mordant Blacks 1, 3, 5, 9, 11, 13, 17, 20, 24, 26, 32, 33, 38; Mordant Blues 1, 3, 7, 9, 13, 37, 47, 49, 55; Mordant Browns 1, 4, 17, 19, 23, 33, 35, 40, 50, 63; Mordant Greens 5, 9, 15, 26, 30; Mordant Oranges 1, 5, 6, 8, 18; Mordant Reds 5, 7, 9, 12, 17, 19, 20, 21, 36, 37; Mordant Violets l, 5, 16, 28, 30; and Mordant Yellows 1, 3, 5, 14, 20, 26, 30, 38.

Due to the great number of existing mordant dyes, and panticularly chrome dyes, it is not possible to give a complete list of such dyes. They can, however, be found in the mentioned Color Index and in Application of Dyestuffs, by J. M. Matthews, pp. 373-4, New York, 1950 (Wiley).

There are three known methods of dyeing wool with mordant dyes: (1) the fiber is first treated with a metal salt and the complex is formed in the dyeing operation (bottom chrome process); (2) the dyeing is carried out in the presence of a chrome salt (meta metal process); (3) the dye is applied to the fiber as usual and the dyeing is then treated with a metal salt solution (top chrome process). In addition to the fact that it is surprising that none of these processes well known for the dyeing of Wool has been applied heretofore for the dyeing of poly- 3,097,044 Patented July 9, 1963 2 propylene fibers, it is also surprising to find that only the process according to the present invention is operative.

The method of the invention is not limited to a process for the dyeing of polypropylene fiber, but also within the scope of the invention is the padding of polypropylene fiber.

The dyeing operation includes the step which comprises contacting polypropylene fibers in an aqueous acid bath with a mordant dye as described above, in presence of a water-soluble metal salt at a temperature of about 212 F. under normal atmospheric pressure for a period of from about 15 minutes to about minutes. An optional additional component of the dye bath comprises an organic solvent which is miscible in said dye bath and which is described more in detail hereinbelow. Said organic solvent, in a specific embodiment of the invention, is employed in a concentration of from about 0.5% to about 5% by weight, preferably about 2% by weight based on total weight of dye bath. Also in a specific embodiment of the invention the dye bath contains an acid, more fully described hereinbelow, in a concentration of from about 2% to about 5% by weight based on dry weight of polypropylene fiber. Further, in a specific embodiment of the invention from about 0.1% to about 10% by weight of mordant dyestufl, preferably mordant dyestuff as described hereinabove, is employed. Moreover, in another specific embodiment of the invention, the liquor ratio of the dye bath to polypropylene fiber ranges from about 8 parts by Weight of dye bath to 1 part by weight of dry fiber, to 30 parts by weight of dye bath to 1 part by weight of dry fiber. The contact time in another specific embodiment of the invention is from about 15 minutes to about 90 minutes.

In another embodiment of the invention, polypropylene fiber is contacted in an aqueous acid bath with a mordant dye in presence of the Water-soluble metal salt at a temperature of from about 213 F. to about 250 F. under super atmospheric pressure suflicient to maintain the bath as a liquid for a period of from about 15 minutes to about 90 minutes. In a specific embodiment, the polypropylene fiber is contacted in said bath which also contains an organic solvent, more fully described hereinbelow. Moreover, in a preferred embodiment of the invention polypropylene fiber is contacted in an aqueous bath, having from about 2% to about 5% by weight of acid and from about 0.5% to about 6% by weight, based on total weight of dye bath, preferably about 2%, of benzyl alcohol as organic solvent, said bath also containing from about 0.5 to about 5% by weight of a water-soluble chrominum salt and from about 0.1% to about 10% by weight of a mordant dye at from about 213 F. to about 250 F. under super-atmospheric pressure, suflicient to maintain the bath as a liquid, for from about 15 minutes to about 90 minutes, all of said percentages by weight being based on the dry weight of said fiber, except that of the organic solvent.

In still another embodiment of the invention polypropylene fiber is padded in a method which comprises first contacting said fiber in an aqueous acid bath with a mordant dye in presence of a water-soluble metal salt, preferably a chrome salt, at a temperature of from about F. to about 180 F. under normal atmospheric pressure, then removing the wet fiber from said bath, and finally steaming said wet fiber under super-atmospheric pressure, preferably from about 8 lbs. per square inch to about 15 lbs. per square inch, for a period of from about 15 minutes to about 90 minutes.

It is understood that the method of padding polypropylene according to the invention may also be practiced with from about 0.5 by weight to about 5% by a weight, preferably about 2% by weight (based on total :eight of padding solution) of the organic solvent, e.g. benzyl alcohol, described hereinabovc.

In the foregoing described embodiments of the invention the acid employed is any suitable acid which is soluble in water and not appreciably harmful to the material to be dyed. For example, mineral acids such as sulphuric acid are sometimes used. More advantageous, however, are certain organic acids, for example the lower alkanoic acids such as e.g. formic acid, acetic acid, propionic acid, butyric acid, etc. In the known metachrome process for dyeing wool, said known process does not involve an acid bath. See, for example, Diserens, L., The Chemical Technology of Dyeing and Printing, translated and revised from the 2nd German ed. by P. Wengraf and H. P. Baumann, vol. 1, especially pages 460 and 461, New York (Reinhold, 1951).

The term polypropylene fiber is understood to embrace not merely raw stock, tow, or individual strands of polypropylene, but also is meant to include piece goods I and any other form of textile stuff.

It is within the scope of the present invention to dye or pad polypropylene fiber with a mordant dye, that is, a dye fully capable of forming a complex with a watersoluble metal salt. One particular type of mordant dyestutf especially useful in dyeing polypropylene is mordant dye used with water-soluble chromium salts which has been described and illustrated hereinabove. It is understood, however, that any suitable water-soluble metal salt is Within the scope of invention: in particular, e.g. the water-soluble chromium salts such as alkali metal chromium salts, e.g. sodium chromates, potassium chromates, ammonium chromates, etc. and also soluble alkaline earth metal chromates, e.g. calcium chromates, magnesium chromates, etc., and chromium halides, especially chromium fluoride, chromium chloride, etc., and chromium low alkanoates, preferably chromium formate, chromium acetate, chromium propionate, etc. It is, of course, understood that mixtures of such salts are also useful and within the scope of the present invention. The concentration of the water-soluble metal salt is advantageously from about 0.5% to about 6% by weight based on the dry weight of the fiber. It is often useful and convenient to employ the same weight percent of chromium salt as dyestuff.

The concentration of dyestutf, in general, ranges from about 0.1% to about by weight, preferably from about 0.5% to about 4% by Weight, based on the dry weight of fiber.

The optional organic solvent which is useful according to the present invention comprises certain organic alcohols, ethers, ketones and combinations thereof. Aromatic as well as aliphatic type solvents are included within the scope of the term organic solvent. Such organic solvent must be readily soluble in water and must have the property of opening up the fiber, thus facilitating the coloring operation with the result that better exhaustion and higher color yields are obtained. The following organic solvents illustrate some of the preferred solvents for use in the present invention, however, other solvents will be apparent from the foregoing, to the skilled textile chemist. It is not intended, therefore, to limit the scope of this invention to those solvents specifically mentioned, i.e. benzyl alcohol, cyclohexanol, propyl alcohol, butyl alcohol, furfuryl alcohol, isophorone, acetophenone, ethylene glycol, phenyl ether, butyl Cellosolve, phenyl Cellosolve, furfural, paraldehyde, n-butyl acetate.

While the scope of the invention embraces, in general, the method of coloring polypropylene fiber, three distinct operations are contemplated: (a) the padding operation, followed by steaming, (b) dyeing at about 212 F. under normal atmospheric pressure, and (c) dyeing at from about 213 F. to about 215 F. under super-atmospheric pressure.

In the padding of polypropylene fiber, the polypropylene fiber is contacted with the aqueous padding liquor at about 120 F. to about 180 F. for a time sufiicient to impregnate the fiber with the dye liquor. The time of 5 contact is not critical. After the impregnation of fiber with dye liquor the wet impregnated fiber is subjected to steaming at super-atmospheric pressure, preferably from about 8 lbs. per square inch to about lbs. per square inch. Upon completion of the steaming operation, the dyed polypropylene is washed, e.g. with cold water.

in the dyeing of polypropylene fiber at normal atmospheric pressure it has been found that a temperature of about 212 F. produces best results. The contact time is generally from about 15 minutes to about 90 minutes, preferably from about 45 minutes to about 60 minutes.

In the dyeing of polypropylene fiber at super-atmospheric pressure it has been found that good results are obtained at temperatures just above 212 F. and better results are obtained at a temperature of about "250 F., while maintaining sufficient super-atmospheric pressure above 212 F. to assure that the dye bath remains a liquid. The contact time also is generally from about 15 minutes to about 90 minutes, preferably from about 45 minutes to about 60 minutes.

It has been found that the liquor ratio, i.e. the relationship between weight of dye bath and weight of fiber to be dyed, is in the range of from about 8 parts dye bath to one part fiber, to about 30 parts dye bath to 1 part fiber. In small scale operations a liquor ratio of about to 1, to to 1 has been found to be satisfactory. On a larger scale the liquor ratio is advantageously 15 to 1, to 10 to 1 and may also be 8 to 1.

It has been found also that best results are obtained when a suitable organic solvent, as described hereinabove, is employed, however, the invention is practicable and useful even without said solvent.

The following examples merely illustrate the invention but do not limit the same in any way. Unless otherwise noted, parts and percentages are by weight, based on the dry Weight of fiber. The relationship of parts by weight to parts by volume is as that of grams to cubic centimeters. Temperatures are in degrees Fahrenheit.

Example 1 said solution. The padding is carried out at 120 at the rate of yards per minute of fiber, after which the padded fibers, without drying, are transferred to a steam chamber and steamed under 15 lbs. pressure for 4-5 minutes. True shade development occurs during the steaming operation in which C.-I. Mordant Violet 1 changes from a weak, dull, reddish violet, to a bright violet.

If, in the foregoing example, a 1% solution of each of the following colors is used, then true shade development also occurs in each case:

(3.1. Mordant Blue 1 Cl. Mordant Blue Cl. Mordant Yellow 5 C.-I. Mordant Orange 8 Cl. Mordant Red 36 Cl. Mordant Brown 17 Cl. Mordant Black 13 Cl. Mordant Black 17 The following table indicates the chemical structure of some of the dyestufis which are illustrated in Examples l-l6:

C.I. 14130Mordant Yellow 5:

NaO O (I) ([30 ONa CH3 /COOH QM CODE 0211 C.I. 43830-Mo1'dant Blue 1:

OOONa COONa 0.1. 43 835-Mordant Blue 55:

O O O Na C1. 63615Mordant Black 13:

Prepared by: Condense 2-chioro or bromo -1,4-dihydroxyanthraquinone with aniline and sulfonate.

SOsNa Cl. 15705M0rdant Black 17:

Example 2 6 of the following colors is used, then true shade development occurs in each case:

C.I. Mordant Violet 1 Cl. Mordant Yellow 5 Cl. Mordant Blue 55 i Cl. Mordant Orange 8 Cl. Mordant Red 36 Cl. Mordant Brown 17 Cl. Mordant Black 13 Cl. Mordant Black 17 Equally good results are obtained if, in the foregoing operation 2% formic acid is used in place of the acetic acid. Likewise, if 2% of either chromium acetate or chromium fluoride is substituted for the sodium bichromate, similarly good results are obtained.

If, in Examples 1 and 2, 2% by :weight (based on total weight of dye solution) of benzyl alcohol or of isophorone is employed in the padding solution, then improved results are obtained. For example, with the 2% by weight (based on total solution) of ibenzyl alcohol better exhaustion is obtained, as well as better color yield.

Example 3 A dye bath is prepared containing an aqueous solution of 2% Cl. Mordant Yellow 5, 4% sodium bichromate and 3% acetic acid, said bath having a liquor ratio of 30 parts dye solution to 1 part of fiber. The dye bath having the polypropylene fiber therein is heated during 30 minutes to 250 and held therefor 60 minutes, pressure being maintained at 18 lbs. per square inch to assure that the bath remains as a liquid. The bath is then cooled to room temperature and cautiously depressurized. The dyed polypropylene is removed from the bath and washed with water. True development of shade is obtained and hand wash tests at for 15 minutes with 1% soap solution in water show that the color does not lose depth. Fadeometer tests, moreover, show that all the dyed polypropylene fibers possess good light fastness properties.

If, in the foregoing dyeing operation, a 3% Cl. Mordant Red 36 and 6% bichromate, or 3% Cl. Mordant Orange 8 and 6% bichromate, or 1% Cl. Mordant Blue 1 and 2% bichromate, or 1.5% CI. Mordant Violet 1 and 3% bichromate, respectively, are used in place of the 2% Cl. Mordant Yellow 5 and 4% bichromate, then equally good results are obtained.

If, in all of the foregoing illustrations of dyeing at 250 and 18 lbs. pressure, either 2% by weight (based on total solution) of benzyl alcohol or 2% by weight (based on total solution) of isophorone is added to the dye bath, then improved results are obtained. With 2% by Weight of benzyl alcohol in the dye bath, for example, better exhaustion and higher color yields are obtained.

Example 4 A dye bath is prepared containing an aqueous solution of 1.5 C.I. Mordant Violet 1, 1.5 sodium bichromate and 3% formic acid, said ba-th having a liquor ratio of 20 parts of dye to 1 part of fiber. The bath having the polypropylene fiber therein is heated to 212 over a 20 minute period and held there for 1 hour, after which the bath is cooled to room temperature and the dyed polypropylene washed with water.

If 2% of sodium bicromate is used instead of 1.5 equally good results are obtained. Likewise, if instead of sodium bichromate, either chromium acetate or chromium fluoride in amounts of 2%, 3% or 4%, respectively, are employed, similarly good results are obtained.

Example 5 A dye bath is prepared containing an aqueous solution of 0.5% of Cl. Mordant Yellow 1, 0.5% of sodium bichromate, 5% of acetic acid and 2% by weight (based on total solution) of benzyl alcohol, said bath having a liquor ratio of parts dye solution to 1 part fiber. The dye bath, having the polypropylene fiber therein, is heated over a 20 minute period to 212. The bath is held at 212 for 1 hours. Afterward, the bath is cooled to room temperature and the dyed polypropylene is Washed with water. Exhaustion tests with wool flannel show that most of the color is taken up by the polypropylene fiber. Good pileup and color yield is observed. If, instead of 0.5% of color and of bichromate, 3% each of color and of bichromate is employed under the same conditions, then equally good results are obtained.

Example 6 Polypropylene fiber is dyed in the same manner as in Example 5, except that 0.5% of CI. Mordant Blue 1 is used instead of Cl. Mordant Yellow 5. Similar results are obtained when 3% of Cl. Mordant Blue 1 is used.

Example 7 Polypropylene fiber is dyed in the same manner as in Example 5, except that 0.5 of Cl. Mordant Violet 1 is used instead of Cl. Mordant Yellow 5. Similar results are obtained when 3% of Cl. Mordant Violet '1 is used.

Example 8 Polypropylene fiber is dyed in the same manner as in Example 5, except that 0.75% of Cl. Mordant Orange 8 and 0.75% of sodium bichromate are used. Good results are also obtained with this same color if the proportion of color and also of bichromate is changed to 4%.

Example 9 Polypropylene fiber is dyed in the same manner as in Example 5, except that 4% of Cl Mordant Blue 55 is used as the color and the sodium bichromate is employed in the amount of 4%.

Example 10 Polypropylene fiber is dyed in the same manner as in Example 5 except that 2% of Cl. Mordant Black 13 is used as the color and the sodium bichromate is employed in the amount of 2%.

Example 11 A dye bath is prepared containing an aqueous solution of 0.5% of Cl. Mordant Yellow 5, 0.5% of sodium bichromate, 5% of acetic acid and 2% by weight (based on total weight of solution) of benzyl alcohol, said bath having a liquor ratio of parts dye solution to 1 part fiber. The dye bath having the polypropylene therein is heated over a. period of 30 minutes to 250. Pressure is maintained to assure that the bath remains in the liquid state. The bath is held at 25 0 for minutes and then cooled to room temperature and cautiously depressurized, after which the dyed polypropylene fiber is removed and washed with water. Exhaustion tests with wool flannel are good and excellent color yield is obtained. The shade is full, clear and very similar to that obtained on wool which has been dyed by the top chrome process.

If in the foregoing dyeing with Cl. Mordant Yellow 5, 3% of color and 3 of bichromate are used, then equally good results are obtained. Also, if 2% by Weight (based on solution) of isophorone is substituted for the benzyl alcohol, similar results are obtained.

Example 12 Example 13 Polypropylene fiber is dyed in the same manner as in Example 11, except that 0.5 of Cl. Mordant Violet 1 is used instead of Cl. Mordant Yellow 5. Similar results are obtained when 3% of Cl. Mordant Violet 1 is used.

Example 14 Polypropylene fiber is dyed in the same manner as in Example 11, except that 0.75% of Cl. Mordant Orange 8 and 0.75% of sodium bichromate are used. Good results are also obtained with this same color if the proportion of color and also of bichroma-te is changed to 4%.

Example 15 Polypropylene fiber is dyed in the same manner as in Example 11, except that 4% of Cl. Mordant Blue 55 is used as the color and the sodium bichromate is employed in the amount of 4% Example 16 Polypropylene fiber is dyed in the same manner as in Example 11, except that 2% of Cl. Mordant Black 13 is used as the color and the sodium bichromate is employed in the amount of 2%.

What is claimed is:

1. The method of dyeing polypropylene fiber by the simultaneous interaction of dye, water soluble chromium sal-t, acid and fiber in aqueous dye bath, which comprises contacting said fiber in said bath with a mordant dye in presence of said water-soluble chromium salt for a period of from about 15 minutes to about minutes at a temperature of from about 212 to about 250 F., the ratio of said dye to said chromium salt ranging from about 1:1 to about 1:2 by Weight, based on the dry weight of the fiber.

2. The method of dyeing polypropylene fiber, according to claim 1, wherein said aqueous acid dye bath also contains a minor proportion of an organic water-miscible solvent selected from the group consist-ing of benzyl alcohol, cyclohexanol, propyl alcohol, butyl alcohol, furfuryl alcohol, isophorone, acetophenone, ethylene glycol, phenylether, butyl Cellosolve, phenyl Cellosolve, furfural, paraldehyde and n-butyl acetate.

3. The method or" dyeing polypropylene fiber, according to claim 1, wherein said aqueous acid bath contains (a) from about 2% to about 5% by weight of a water-soluble acid, which ranges in strength from that of acetic acid to that of formic acid (b) from about 0.5 to about 5% by volume of benzyl alcohol,

(0) from about 0.5 to about 4% by Weight of mordant dye, and

(d) water soluble chromium salt in a dye: salt ratio 7 of from about 1:1 to about 1:2 by weight,

all said percentages by weight being based on dry Weight of said polypropylene fiber.

4. The method of padding polypropylene fiber, by the simultaneous interaction of dye, water soluble chromium salt, acid and fiber in a liquid aqueous padding bath which comprises contacting said fiber in said aqueous padding bath with a mordant dye in presence of said salt at a temperature of from about F. to about 180 F, the dye: salt ratio ranging from about 1:1 to about 1:2 by weight, based on the padding bath solution, removing excess padding dye bath liquor from said wet fiber, and steaming the so-obtained wet fiber under superatmospheric pressure.

5. The method of padding polypropylene fiber according to claim 4, wherein the wet fiber is steamed at a pressure of from about 8 to about 15 lbs. per square inch for a period of from about 15 to about 90 minutes.

6. The method of padding polypropylene fiber, according to claim 5, wherein said aqueous acid bath contains a minor proportion of an organic water-miscible solvent, selected from the group consisting of benzyl alcohol, cy clohexanol, propyl alcohol, butyl alcohol, furfuryl alcohol, isophorone, acetophenone, ethylene glycol, phenylether, butyl Cellosolve, phenyl Cellosolve, furfural, paraldehyde and n-butyl acetate.

9 7. The method of padding polypropylene fiber, accord ing to claim 6, wherein said aqueous acid bath contains (a) from about 2% to about by weight of watersoluble acid, which ranges in strength from that of acetic to that of formic acid, (b) from about 0.5% to about 5% by volume of benzyl alcohol as additional solvent, (0) 2% by weight of a water-soluble chromium salt,

and (d) 1% by weight of a mordant dye, all said percentages by weight being based on the weight of said aqueous acid bath.

8. A colored composition of matter according to claim 7, wherein said mordant dye is selected from. the group consisting of (a) the dyestufi of the formula (12) the dyestuff of the formula GOONs C IOONa 10 (d) the dyestuif of the formula (e) dyestufii of the formula and SO NB.

9. A colored composition of matter which consists essentially of polypropylene fiber and, as dyeing agent bound thereto a. chromium complexed mordant dye.

References Cited in the file of this patent UNITED STATES PATENTS 2,520,105 Millson et a1. Aug. 22, 1950 2,534,647 Widmer et a1. Dec. 19, 1950 2,886,471 Bruce et .al. May 12, 1959 FOREIGN PATENTS 809,495 Great Britain Feb. 25, 1959 814,582 Great Britain June 10, 1959 OTHER REFERENCES Colour Index, vol. 1, Amer. Asso. of Textile Chemists and Colorists, Lowell, Mass, 1956, pp. 1405, 14 81, 1525, 159 1, and 1593.

Nomura et al., JSDC, May 1958, pp. 359 371.

Finch, Fibres and Plastics, January 1960, pp. 14-16. 

1. THE METHOD OF DYEING POLYPROPYLENE FIBER BY THE SIMULTANEOUS INTERACTION OF DYE, WATER SOLUBLE CHROMIUM SALT, ACID AND FIBER IN AQUEOUS DYE BATH, WHICH COMPRISES CONTACTING SAID FIBER IN SAID BATH WITH A MORDANT DYE IN PRESENCE OF SAID WATER-SOLUBLE CHROMIUM SALT FOR A PERIOD OF FROM ABOUT 15 MINUTES TO ABOUT 90 MINUTES AT A TEMPERATURE OF FROM ABOUT 212* TO ABOUT 250*F., THE RATIO OF SAID DYE TO SAID CHROMIUM SALT RANGING FROM ABOUT 1:1 TO ABOUT 1:2 BY WEIGHT, BASED ON THE DRY WEIGHT OF THE FIBER. 